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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

26691 results found.

  1. EP250702a: WFST optical observations
  2. EP250704a: COLIBRÍ optical counterpart candidate
  3. EP250704a: Einstein Probe detection of an X-ray transient
  4. GRB 250704A: REM detection of the optical afterglow
  5. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  6. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  7. GRB 250704A: SVOM detection of a burst
  8. GRB 250702F: Swift/UVOT Detection
  9. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  10. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  11. GRB 250702F: Swift-XRT refined Analysis
  12. GRB 250702F: Fermi GBM Observation
  13. GRB 250702F: Leavitt Observatory optical observations
  14. GRB 250702F: AKO Optical Afterglow Detection
  15. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  16. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  17. GRB 250702A: GECAM-B detection
  18. GRB 250702F: Skynet Optical Observations
  19. GRB 250424A: VIRT Optical Upper Limit
  20. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  21. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  22. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  23. GRB 250702F: TRT Optical Observation
  24. GRB 250703A: DDOTI Optical Upper Limit
  25. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  26. GRB 250702F: REM optical afterglow detection
  27. GRB 250702F: DDOTI Optical Observation
  28. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  29. GRB 250702F: COLIBRÍ Observations of the Afterglow
  30. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  31. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  32. GRB 250702F: Enhanced Swift-XRT position
  33. GRB 250702F: NOT observations of the optical afterglow
  34. GRB 250702F: Swift detection of a burst with an optical counterpart
  35. GRB 250702F: Fermi GBM Final Real-time Localization
  36. GRB 250702E: Fermi GBM Final Real-time Localization
  37. Konus-Wind detection of GRB 250627A
  38. GRB 250702A: Fermi GBM Detection
  39. GRB 250702C: Fermi GBM Final Real-time Localization
  40. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  41. GRB 250702B: Fermi GBM Final Real-time Localization
  42. GRB 250702A: Fermi GBM Final Real-time Localization
  43. LIGO/Virgo/KAGRA S250701bq: Identification of a GW compact binary merger candidate
  44. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  45. GRB 250628B: Swift-XRT observations
  46. GRB 250628B: EP-FXT counterpart detection
  47. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate
  49. GRB 250628A: REM optical/NIR upper limits
  50. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate
  51. GRB 250628B: SVOM detection of a long burst
  52. GRB 250628A: VLT/X-shooter upper limits
  53. GRB 250628A: Swift/UVOT Upper Limits
  54. GRB 250628A: Swift-XRT refined Analysis
  55. GRB 250628A: Enhanced Swift-XRT position
  56. GRB 250628A: Swift detection of a burst
  57. GRB 250625A: Swift-BAT refined analysis
  58. GRB 250625A: Leavitt Observatory afterglow detection
  59. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  60. The EP-WXT trigger 01709179435 is likely a new outburst of the CV SS Cyg
  61. GRB 250625A: SVOM/C-GFT upper limit in early phase
  62. GRB 250625A: GECAM-B detection
  63. GRB 250625A: Swift/UVOT Upper Limits
  64. GRB 250625A: ABObservatory afterglow detection
  65. GRB 250625A: OHP/T193 optical detection
  66. GRB 250625A: COLIBRÍ optical observations
  67. GRB 250625A: Swift-XRT refined Analysis
  68. GRB 250625A: JinShan optical observations
  69. GRB250625A: Fermi GBM Observation
  70. GRB 250620B: Fermi GBM Observation
  71. GRB 250625A: SAO RAS possible optical afterglow
  72. GRB 250625A: Enhanced Swift-XRT position
  73. GRB 250625A: Swift detection of a burst
  74. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  75. GRB 250620A: AstroSat CZTI detection
  76. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  77. GRB 241018A: Maidanak optical observations
  78. GRB 250620C: AstroSat CZTI detection
  79. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  80. GRB 250521A: VZLUSAT-2 detection
  81. IPN triangulation of GRB 250620C (long/bright)
  82. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  83. GRB 250620C: SVOM/GRM observation
  84. GRB 250620A: SVOM/GRM observation of a short burst
  85. GRB250620A: Fermi GBM Observation
  86. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  87. GRB 250619B: Fermi GBM Observation
  88. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  89. GRB250620C: Fermi GBM Observation
  90. GRB 250506A - SVOM/ECLAIRs Refined analysis
  91. The EP-WXT trigger 01709179071 is likely a flaring star
  92. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  93. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  94. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  95. GRB 250617B: Nickel telescope optical observations
  96. GRB 250615A: Kilonova-Catcher optical upper limits
  97. GRB 250617B: Assy AZT-20 Optical Observations
  98. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  99. GRB 250617B: Swift/UVOT Detection
  100. GRB 250617B: Kilonova-Catcher optical afterglow detection

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